The invention relates generally to a method for forming a fine pattern in a semiconductor device
In order to manufacture smaller semiconductor devices, patterns have become smaller. Research has been directed to developing resists and exposers for obtaining fine patterns.
Regarding exposers, KrF (248 nm) and ArF (193 nm) have been applied as an exposure light source, and attempts have been made to use short wavelength light sources such as F2 (157 nm) or EUV (13 nm; extreme ultraviolet light) or to increase numerical apertures (NA).
However, when new light sources such as F2 are applied, a new exposer is required, and increased manufacturing costs result. Also, the increase of numerical apertures degrades the focus depth width.
Although an immersion lithography process with an immersion solution having a high refractive index has been developed, it is difficult to apply the process on a mass production scale.
Meanwhile, a fine pattern having a resolution beyond the lithography limit has been formed by a double exposure method. However, it is difficult to secure margins of overlapping and arrangement, which results in excessive production cost and time.